Prior Art 1: An old-fashioned wireless bike brake light, which emits radio to trigger brake light when a bike rider depresses the brake levels. The drawbacks include (1) a rider needs to install sensors on both brake levels of a bike, which actually causes a practical problem in installation because a different kind or brand of bike has the brake level of different shape or design. (2) For sports like skiing or snowboarding, such a product would not work because it does not have the apparent brake mechanisms that can serve as triggering devices.
Prior Art 2: There were several severe brake light inventions that employ accelerometers, such as U.S. Pat. No. 6,249,219, a severe braking light system. It may work for responding to “severe” braking, but may not work for “light” braking function. It is because the gravitational effect may cause significant errors on deceleration detecting. Given detecting “light” deceleration of 0.1 G for example, if a bike is just stopped on a downhill slope of 10 degrees, the brake light will mistakenly light up because the G-force of 0.17 G will exceed deceleration threshold of 0.1 G although the bike is actually still, not decelerating. If detecting “severe” brake, then it would be a forgiven error. Given detecting “severe” deceleration of 2.0 G for example, if a bike is just stopped on a downhill slope of 10 degrees, the brake light will not mistakenly light up because G-force of 0.17 G is still very far from the deceleration threshold of 2.0 G.